To explore the nature of MM2E and MM2W,
we first consider their observed 1.3 mm continuum
brightness temperatures (\(T_b\) ), which provide strict lower limits for their physical temperatures of 68.4 K and 64.6 K respectively (Table ). These high temperatures signify internal heating, as external heating
[1]}, [2]}, [3]} could account for dust temperatures of at most \(\sim \) 23 K, based on simple estimates [4]}.
With evidence for both internal heating and a bipolar outflow (§REF ), we interpret MM2E and MM2W as deeply embedded protostars, which leads to the conclusion that MM2 is not starless and emphasizes the importance of high-resolution (sub)millimeter observations for detecting protostars and their outflows in candidate high-mass starless clumps and cores [5]}, [6]}, [7]}, [8]}.
